Researchers use PEM fuel cell reactor to convert biomass-derived acetone into isopropanol; new biomass to fuels pathway
03 October 2012
A team from the University of Wisconsin-Madison, University of Massachusetts-Amherst and Gwangju Institute of Science and Technology of South Korea has demonstrated the feasibility of using proton-exchange-membrane (PEM) reactors electrocatalytically to reduce biomass-derived oxygenates into renewable fuels and chemicals.
George Huber, UW-Madison professor of chemical and biological engineering, and his collaborators used a PEM fuel cell reactor to reduce the model biomass compound acetone into isopropanol— a chemical compound with a wide variety of pharmaceutical and industrial applications, including as a gasoline additive—on an unsupported platinum cathode. The advance paves the way for researchers to convert biomass molecules such as glucose into hexanes, which are significant components of gasoline currently derived by refining crude oil.
A paper on their work is published in the journal ChemSusChem.
Unlike other technologies that use large quantities of hydrogen gas to convert biomass to biofuels, the team’s process is driven by electricity. To reduce biomass molecules into fuel, Huber’s team feeds water into the anode side and passes an electric current through the water to generate protons and electrons. The electrons run through a circuit and the protons pass through the proton-exchange membrane to the cathode side, where they generate hydrogen. The hydrogen reacts with the biomass molecule and reduces it to fuel, while oxygen exits the system.
The current efficiency (the ratio of current contributing to the desired chemical reaction to the overall current) and reaction rate for acetone conversion increased with increasing temperature or applied voltage for the electrocatalytic acetone/water system. The reaction rate and current efficiency went through a maximum with respect to acetone concentration. The reaction rate for acetone conversion increased with increasing temperature for the electrocatalytic acetone/hydrogen system. Increasing the applied voltage for the electrocatalytic acetone/hydrogen system decreased the current efficiency due to production of hydrogen gas.
—Green et al.
Huber’s team demonstrated the biomass-to-biofuel reduction process in a continuous-flow reactor. The process yields 50% more liquid fuel over ethanol fermentation processes.
At the production level, the process also could be modular, making it potentially a scalable technology with which reactors could be close to the biomass, and run at night with less expensive electricity, says Huber.
In future work, Huber hopes to improve the catalysts and membranes in the fuel cell to make the process more efficient. While the team used acetone and a few other molecules as their proof-of-concept, one of Huber’s goals is to repeat the process with sugar.
Huber received support for the research from the University of Massachusetts Commercial Venture and Intellectual Property Technology Development Fund.
Resources
Green, S. K., Tompsett, G. A., Kim, H. J., Kim, W. B. and Huber, G. W. (2012), Electrocatalytic Reduction of Acetone in a Proton-Exchange-Membrane Reactor: A Model Reaction for the Electrocatalytic Reduction of Biomass. ChemSusChem. doi: 10.1002/cssc.201200416
Conversion of hexoses to hexane (and pentoses to pentane?) would be a huge advance. As hydrocarbons, they self-separate from water by gravity and require no distillation.
Converting all of the carbon in a biomass stream to hydrocarbons would solve the motor fuel problem. The issue is going to be finding a catalyst cheaper than Pt, because a cell for intermittent operation on excess electricity needs to have low capital cost to be competitive.
Posted by: Engineer-Poet | 03 October 2012 at 04:31 PM
The element is K.
Posted by: EVryman | 03 October 2012 at 08:26 PM
Oh my bad...I had a brain fart. Not K lol. I must be thinking about catalytic converters or something.
Posted by: EVryman | 03 October 2012 at 08:28 PM
Oh god I'm tired. I meant Potassium, K not platinum Pt. Jeeez....
The work sounds intriguing. Will the burning of this as fuel release carbon? If so, isn't it a really expensive way to make no difference? If the end result is carbon neutral or even reduced, I'm all for it.
Posted by: EVryman | 03 October 2012 at 08:31 PM
It's better to use waisted co2 then any other feedstock like they did in this experiment. It's been a while that i say to install a co2 converter in the exhaust flow of gasoline/diesel cars and truck and also the co2 output of electrical powerplant and convert this into fuels and recirculate it at the input.
Posted by: A D | 04 October 2012 at 09:09 AM
You're not familiar with the Second Law of Thermodynamics, are you?
Posted by: Engineer-Poet | 04 October 2012 at 11:01 AM
makes more sense than the BS about powering cars with hydrogen.
Posted by: dursun | 08 October 2012 at 01:23 PM